The vacuum-casting industry designs tools that function as and makes molds from which additional articles are cast. Molds currently used in the vacuum-casting industry are made by serially applying plural layers of various materials to a master mold. These conventional molds generally have at least one layer, usually the first layer applied to the master mold, made from aluminized gel coats. Aluminized gel coats are relatively quite expensive, typically costing about $11-$12/pound.
After the first layer is applied to the master mold, additional "back up" layers are serially applied by hand over this layer to form a mold. Vacuum-casting methods subject these molds to significant stresses, and the molds therefore must have sufficient structural integrity so that they can withstand these stresses and be useful for their intended purposes. Molds made using conventional technology require a mold wall thickness of at least about 5/16 inch to about 3/8 inch, which thicknesses are achieved by serially applying back up layers to the master mold until the desired mold thickness is obtained. Back up layers for vacuum-casting molds often comprise fiberglass and an aluminized tooling resin. The cost of the materials used to make the back-up layers, while significantly less than that for aluminized gel coats, still is about $5-$6/pound.
Conventional molds used by the vacuum-casting industry have a part production capacity of only about 1,000 parts. That is, the molds must be replaced after about 1,000 parts are made using such molds. Moreover, conventional molds currently used by the vacuum-casting industry have to be repaired after producing only about 75-100 parts. These two factors, the part production capacity of the mold and the need to repair the mold frequently, plus the material costs required to produce conventional vacuum-casting molds, indicate that there is a need for new materials and methods for making various molds useful for practicing vacuum-casting processes.